Thermostatic two-pole switch

ABSTRACT

A bipolar thermostatic switch has a thermally-responsive, snapacting, domed bimetallic dished element disposed in a housing to be movable to an inverted dished configuration when the element is subjected to a selected temperature, has two arms mounted in the housing for movement between open and closed circuit positions engaging or disengaging complementary contacts for opening and closing two electrical circuits, and has a pair of motion transfer members disposed in coaxial telescoping relation to each other with one end of each of the motion transfer members engaging the dished element, with an opposite end of the outer motion transfer member engaging one of the contact arms, and with the opposite end of the other motion transfer member extending through an aperture in said one contact arm to engage the second contact arm, whereby snap-acting movement of the dished element to an inverted dished configuration in response to the dished element being subjected to said selected temperature is effective to move each of the contact arms between selected circuit positions of said arms.

ited States Patent 11 1 Po Nov. 18, 1975 I54] THERMOSTATIC TWO-POLE SWITCH [57] ABSTRACT [75] Inventor: Walter Pohl, Naples, Italy [73] Assignee: Texas Instruments Incorporated, A bipolar thermostatic Switch has a thermally Dallas Tex responsive, snap-acting, domed bimetallic dlshed element disposed in a housing to be movable to an in- [22] Flled' 1974 verted dished configuration when the element is sub- [21] App]. No.1 518,008 jected to a selected temperature, has two arms mounted in the housing for movement between open [30] Apphcatmn Pnorlty Data and closed circuit positions engaging or disengaging Nov. 12, 1973 Italy 36089/73 complementary contacts for opening and closing two [52] CL H 337/337, 337/343, 337/354 electrical circuits, and has a pair of motion transfer [51] Int z HOIH 37/52 members disposed in coaxial telescoping relation to [58] Field of B8 4144 each other with one end of each of the motion transfer 337/46 members engaging the dished element, with an opposite end of the outer motion transfer member engaging [56] References Clted one of the contact arms, and with the opposite end of UNITED STATES PATENTS the other motion transfer member extending through 3,500,277 3/1970 Nardulli ..'337/343 an aperture in Said one Contact arm to engage the 3,852,698 12/1974 Schmitt 337/354 Q Contact arm, whereby Snap-acting movement of the dished element to an inverted dished configuration 1 916223 PATENTS OR APPLICATIONS in response to the dished element being subjected to 4/1968 Germany 337/354 Primary ExaminerJ. D. Miller Assistant Examiner-Fred E. Bell Attorney, Agent, or FirmJohn A. Haug; James P. McAndrews; Russell E. Baumann said selected temperature is effective to move each of the contact arms between selected circuit positions of said arms.

4 Claims 1 Drawing Figure U.S. Patent Nov. 18, 1975 THERMOSTATIC TWO-POLE SWITCH It is an object of this invention to provide a thermostatic switch in which two electrical circuits initially closed are opened when the switch is subjected to a temperature above a selected value and are reclosed when the temperature to which the switch is subjected subsequently falls below a selected value.

Briefly described, the bipolar thermostatic switch of this invention comprises a housing inside which is disposed a preformed bimetallic element of the thermally responsive snap-acting domed dish or calotte type on which bear two coaxially disposed controlled elements to actuate independent contacts in accordance with the reversal of the curvature of the bimetallic element at a response temperature.

Other objects and advantages and details of the thermostatic switch of this invention are shown in the following description of a preferred embodiment of the present invention, the description referring to FIG. 1 of the drawing which comprises an axial cross-section view of the thermostatic switch of this invention.

As shown in the drawing, the bipolar thermostatic device of this invention comprises lower and upper cases 1 and 4 fastened to each other. The case 1 provides a seat 2 on which is disposed a metallic lid 3 in contact with a medium or atmosphere in which temperature variations occur. To the said case 1 are anchored the contact elements 14 and 15 and the outer terminals 16 and 17; to case 4 are anchored the other two contact elements 10 and 11 with the outer terminals 12 and 13; and to case 4 is further fastened the closing cover 18.

The metallic lid 3 is shaped in such a way as to present a plane seat 5 in the form of a circular crown on which bears a bimetallic disk 6, said disk comprising a thermally-responsive snap-acting bimetallic element of a calotte or domed, dished configuration which is preformed in such a way that its curvature inverts at a certain temperature T.

At the center of the bimetallic disk 6 bear two control members 8 and 9 which are coaxial and slide into one another after the manner of a telescope, the control members being guided in their axial movement by a hole 7 made in the base 1. The control members include rod 8 which acts on the elastic contact blade or element and a tubular rod member 9 acts on the elastic contact element or blade 14.

As shown, the contact blade 10 is disposed opposite contact 11. The contact elements 10 and 11 are mounted to be integral with anchoring terminals 12 and 13. The contact blade 14 is disposed opposite contact 15. The contact elements 14 and 15 are mounted to be integral with anchoring terminals 16 and 17.

In normal operation, flange 3 is in contact with a medium or atmosphere (solid, liquid, or gaseous) for which the temperature is to be controlled. Heat from this medium is propagated through the flange 3 to the bimetallic disk 6 as will be understood, At an increase of the temperature of the medium to which the flange 3 is exposed, the disk reaches the critical temperature at which it reverses its curvature and moves the motion 2 transfer members or control members 8 and 9 upward. In this way, the control member 8 opens the circuit formed by the contacts 10 and 11. As shown, the control member 8 extends through an aperture in the contact blade 14. The control member 9 opens the circuit formed by the contacts 14 and 15.

At a decrease in the temperature of the medium to which the flange 3 is exposed, the bimetallic disk is lowered to the temperature at which, considering the differential temperature of such bimetallic disks, the initial configuration of the disk and the initial conditions of the switch are restored.

The operation of the thermostatic switch of this invention has been described above in reference to the thermostatic switch in which the contact elements 10 and 11 and 14 and 15 are initially closed and are opened upon the occurrence of a certain temperature value in a medium to which the flange 3 is exposed. By reversing the orientation of the cavity of the bimetallic disk, a thermostatic switch is obtained in which the contact elements 10 and 11 and 14 and 15 are initially open and are closed at the occurrence of a selected temperature value in such medium. In addition, an electrical connection can be provided which electrically connects the electrical anchoring terminals 13 and 16 as will be understood. Other modifications of the described switch can be made within the scope of this invention.

1 claim:

1. A bipolar thermostatic switch comprising a housing, a thermally responsive, snap-acting bimetallic, dished element adapted to reverse its dished configuration at a predetermined temperature mounted in said housing, a pair of stationary contact means mounted on said housing, a pair of movable contact means mounted on said housing for movement between control positions engaging and disengaging the said respective stationary contact means, and a pair of control elements disposed in coaxial telescoping relation to each other each having one end thereof in engagement with said dished element and having an opposite end thereof in engagement with said respective movable contact means for moving said movable contact means between said circuit positions in response to reversing of the curvature of said dished element at said selected temperature.

2. A switch as set forth in claim 1 wherein said housing supports said control members for movement between said dished element and said movable contact means.

3. A switch as set forth in claim 1 wherein said control members comprise a tubular member of selected length and a rod member of relatively greater length axially slidable in said tube member.

4. A switch as set forth in claim 3 wherein one of said movable contact means is engaged by an end of said tube member, said one movable contact means having an aperture therein, and wherein the other of said movable contact means is engaged by an end of said rod member extending through said aperture. 

1. A bipolar thermostatic switch comprising a housing, a thermally responsive, snap-acting bimetallic, dished element adapted to reverse its dished configuration at a predetermined temperature mounted in said housing, a pair of stationary contact means mounted on said housing, a pair of movable contact means mounted on said housing for movement between control positions engaging and disengaging the said respective stationary contact means, and a pair of control elements disposed in coaxial telescoping relation to each other each having one end thereof in engagement with said dished element and having an opposite end thereof in engagement with said respective movable contact means for moving said movable contact means between said circuit positions in response to reversing of the curvature of said dished element at said selected temperature.
 2. A switch as set forth in claim 1 wherein said housing supports said control members for movement between said dished element and said movable contact means.
 3. A switch as set forth in claim 1 wherein said control members comprise a tubular member of selected length and a rod member of relatively greater length axially slidable in said tube member.
 4. A switch as set forth in claim 3 wherein one of said movable contact means is engaged by an end of said tube member, said one movable contact means having an aperture therein, and wherein the other of said movable contact means is engaged by an end of said rod member extending through said aperture. 